Electronics Engineering

Electronics & Communication Engineering(ECE) deals with the electronic devices, circuits, communication equipment’s like transmitter, receiver, integrated circuits (IC). It also deals with basic electronics, analog and digital transmission & reception of data, voice and video (Example AM, FM, DTH), microprocessors, satellite communication, microwave engineering, antennae and wave progression. It aims to deepen the knowledge and skills of the students on the basic concepts and theories that will equip them in their professional work involving analysis, systems implementation, operation, production, and maintenance of the various applications in the field of Electronics and Communications Engineering.

Electronic communications engineering is the utilization of science and math applied to practical problems in the field of communications. Electronic communications engineers engage in research, design, development and testing of the electronic equipment used in various communications systems. Electronics engineering deals with implementation of applications, principles and algorithms developed within many related fields, for example solid-state physics, radio engineering, telecommunications, control systems, signal processing, systems engineering, computer engineering, instrumentation engineering, electric power control, robotics.

Electronic is a study and use of electrical devices that operate by controlling the flow of electrons or other electrically charged particles. Electronics is a subfield within the wider electrical engineering that covers subfields such as analog electronics, digital electronics, consumer electronics, embedded systems and power electronics.

All of the applications which make our life easier and enjoyable such as Television, Radio, Computers, Mobiles etc. are designed and developed by Electronics and Communication Engineers

Design and maintain satellites, which bring TV, telephone and Internet service into remote and rural regions.

ECE Engineers also creates advanced communication facilities like video conferencing which bring people together from all over the world.

Develops programs for various control and communication systems.

And the electrical engineers are works in the various fields such as the service engineer, software analyst, technical director, field test engineer, senior sales manager, network planning Engineer, customer support engineer, electronic and communications consultant, and research development software engineer, etc.

Electrical engineers are enjoying such modern communication devices as cellular telephones, radios and televisions.

Communication means transferring a signal from the transmitter which passes through a medium then the output I’d obtained at the receiver. (Or) the transferring of message from one place to another place is called communication.

Analog is the process of taking an audio or video signal and translating into electronic pulses. Digital on the other hand is breaking the signal into a binary format. Where the audio or video data is represented by a series of “0”s and “1”s.

Digital signals are immune to noise, quality of transmission and reception is good, components used in digital communication can be produced with high precision and power consumption is also very less when compared with analog signals.

Electronic work on DC and with a voltage range of -48vDC to +48vDC. If the electronic device is plugged into a standard wall outlet, there will be a transformer inside which will convert the AC voltage you are supplying to the required DC voltage needed by the device. Examples are computer, radio, TV, etc.

Electric device use line voltage (120vAc, 240vAC, etc.…). Electric devices can also be designed to operate on DC sources but will be at DC voltages above. Examples are incandescent lights, heaters, fridge, stove, etc…

Modulation is the process of varying some characteristic of a periodic wave with an external signal. Radio communication superimposed this information bearing signal onto carrier Signals. These high frequency carrier Signals can be transmitted over the air easily and are capable of travel long distances. The characteristics (amplitude, frequency, or phase) of the carrier signal are varied in accordance with the information bearing signal. Modulation is utilized to send an information bearing signal over long distance.

Demodulation is the act of removing the modulation from an analog signal to get the original baseband signal back. Demodulation is necessary because the receiver system receives a modulated signal with specific characteristics and it needs to turn it to baseband.

AM: In the amplitude modulation, the amplitude of a carrier signal is varied by the modulating signal. Here information signal is the modulating signal and high frequency signal which is being modulated is the carrier signal. AM is used for video signals for example tv. It ranges from 535 to 1705 KHZ.

FM: Frequency modulation is a system in which the amplitude of the modulated carrier is kept constant, while its frequency is varied by the modulating signal. FM is used for audio signals for example radio. It ranges from 88 to 108 MHZ.

Materials having very low value of conductivity are known as insulators. Insulators completely opposes the flow of charge when a voltage source is applied across its terminals. Usually, insulators contain less than 106free electron per cubic centimeter. Example of insulator is ‘mica’.

Materials having very high value of conductivity are known as conductors. Conductors support a generous flow of change when a voltage source is applied across it terminals. Usually conductor is containing approximately 1021 free elections for cubic centimeter of the material. Example of conductor is `copper’.

Materials having conductivity value between in extreme of an insulator and conductor and semiconductors. Semiconductors conduct moderately (at room temperature) when a voltage source is applied across its terminals. Examples of semiconductor are `silicon’ (

It is a system the output is input are interested related in such a manner that the output quantity is a valuable controlled by input quantity, then the such a system is called control system the output quantity is called control variable are the response and the input quantity is called command signal or excitation.

Feedback in control system is one in which the output is sampled and proportional signal is fed back to the input for automatic correction of the error (any change in desired output) for further processing to get back the desired output.

The role of feedback in control system is to take the sampled output back to the input and compare output signal with input signal for error (deviation from the desired result). Negative feedback results in the better stability of the system and rejects any disturbance signals and is less sensitive to the parameter variations. Hence in control systems negative feedback is considered. The characteristics of the negative feedback are:

Reduction in the gain at the expense of better stability of the system.

Positive feedback is not used generally in the control system because it increases the error signal and drives the system to instability. But positive feedbacks are used in minor loop control systems to amplify certain internal signals and parameters.

An oscillator is a circuit that creates a waveform output from a direct current input. The two main types of oscillator are harmonic and relaxation. The harmonic oscillators have smooth curved waveforms, while relaxation oscillators have waveforms with sharp changes.

Crosstalk is a form of interference caused by signals in nearby conductors. The most common example is hearing an unwanted conversation on the telephone. Crosstalk can also occur in radios, televisions, networking equipment, even electric guitars.

A discrete-time signal is defined by specifying its value only at discrete times, called sampling instants. When the sampled values are quantized and encoded, a digital signal is obtained. A digital signal is obtained from the analog signal by using an analog-to-digital converter. This entire process is referred to as the conversion of signals from analog to digital form.

Bluetooth is designed to be a personal area network, where participating entities are mobile and require sporadic communication with others. It is Omni directional i.e. it does not have line of sight limitation like infra-red does. Ericsson started the work on Bluetooth and named it after the Danish king Harold Bluetooth. Bluetooth operates in the 2.4 GHz area of spectrum and provides a range of 10 meters. It offers transfer speeds of around 720 Kbps.

The load flow study of a power system is essential to decide the best operation existing system and for planning the future expansion of the system. It is also essential for designing the power system.

The components of power system may operate at different voltage and power levels. It will be convenient for analysis of power system if the voltage, power, current ratings of the components of the power system is expressed with reference to a common value called base value.

CDMA stands for Code Division Multiple Access which uses digital format. In CDMA systems several transmissions via the radio interface take place simultaneously on the same frequency bandwidth. User data is combined at the transmitter’s side with a code, then transmitted. On air, all transmission get mixed. At the receiver’s side the same code is used as in the transmitter’s side. The code helps the receiver to filter the user information of the transmitter from incoming mixture of all transmissions on the same frequency band and same time.

The whole of the geographical area is divided into hexagonal shape geometrical area called cell and each cell having its own transceiver. Each BTS (cell site) allocated different band of frequency or different channel. Each BTS antenna is designed in such a way that cover cell area in which it is placed with frequency allotted without interfering other sell signal.

A stop band is a band of frequencies, between specified limits, in which a circuit, such a filter or telephone circuit, does not let signals through, or the attenuation is above the required stop band attenuation level.

Radio frequency (RF) is a frequency or rate of oscillation with the range of about 3HZ to 3GHZ. This range corresponds to frequency of alternating current electrical signals used to produce and detect radio waves since most of this range is beyond the vibration rate that most mechanical systems can respond to, RF usually refers to oscillations in electrical circuits or electromagnetic radiation.

A repeater is an electronic device that receives a signal and retransmits it at a higher level and/or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances without degradation.

When a radio wave travels into the ionospheric layer it experiences refraction due to difference in density. The density of ionospheric layer is rarer than the layer below which causes the radio wave to be bent away from the normal. Also, the radio wave experiences a force from the ions in the ionospheric layer. If incident at the correct angle the radio wave is completely reflected back to the inner atmosphere due to total internal reflection. This phenomenon is called ionospheric reflection and is used in mobile communication for radio wave propagation also known as ionospheric bending of radio waves.

In electronics, a transistor is a semiconductor device commonly used to amplify or switch electronic signals. The transistor is the fundamental building block of computers, and all other modern electronic devices. Some transistors are packaged individually but most are found in integrated circuits.

An operational amplifier, often called an op-amp, is a DC-coupled high-gain electronic voltage amplifier with differential inputs and, usually, a single output. Typically, the output of the op-amp is controlled either by negative feedback, which largely determines the magnitude of its output voltage gain, or by positive feedback, which facilitates regenerative gain and oscillation.

Barkhausen criteria, without which you will not know which conditions, are to be satisfied for oscillations. “Oscillations will not be sustained if, at the oscillator frequency, the magnitude of the product of the transfer gain of the amplifier and the magnitude of the feedback factor of the feedback network (the magnitude of the loop gain) are less than unity”. The condition of unity loop gain -A? = 1 is called the Burkhouse criterion. This condition implies that A? = 1and that the phase of – A? is zero.

The amount of time between the creation and disappearance of a free electron is called the life time. It varies from a few nanoseconds to several microseconds depending how perfect the crystal is and other factors.

The diffusion of charge carriers is a result of a gradient of carrier concentration (i.e, the difference of carrier concentration from one region to another). In this case concentration of charge carriers (either electrons or holes) tend to distribute themselves uniformly throughout the semiconductor crystal. This movement continues until all carriers are evenly distributed throughout the material. This type of movement of charge carriers is called diffusion current.

Compare with the conductivity of metals. With the increase in temperature, the concentration of charge carriers increases resulting in increase in conductivity of semiconductors. The conductivity of metal decreases with the increase in temperature.

FDMA: FDMA (Frequency Division Multiple Access) is the process of dividing one channel or bandwidth into multiple individual bands, each for use by a single user. Each individual band or channel is wide enough to accommodate the signal spectra of the transmissions to be propagated. The data to be transmitted is modulated on to each subcarrier, and all of them are linearly mixed together. Only disadvantage is Inflexible, frequencies are scarce resource

TDMA: TDMA (Time Division Multiple Access) is a digital technique that divides a single channel or band into time slots. Each time slot is used to transmit one byte or another digital segment of each signal in sequential serial data format. This technique works well with slow voice data signals, but it’s also useful for compressed video and other high-speed data. Only disadvantage is Guard space needed (multipath propagation), synchronization difficult

OFDMA: OFDMA (Orthogonal frequency division multiplexing) is the access technique used in Long-Term Evolution (LTE) cellular systems to accommodate multiple users in a given bandwidth. OFDM is a modulation method that divides a channel into multiple narrow orthogonal bands that are spaced so they don’t interfere with one another. Each band is divided into hundreds or even thousands of 15-kHz wide subcarriers.

SDMA: SDMA (Space-division multiple access) uses physical separation methods that permit the sharing of wireless channels. For instance, a single channel may be used simultaneously if the users are spaced far enough from one another to avoid interference. Known as frequency reuse, the method is widely used in cellular radio systems. Cell sites are spaced from one another to minimize interference. Only disadvantage is Inflexible, antennas typically fixed.

CDMA: CDMA (Code Divisional Multiple Access) is another pure digital technique. It is also known as spread spectrum because it takes the digitized version of an analog signal and spreads it out over a wider bandwidth at a lower power level. This method is called direct sequence spread spectrum (DSSS) as well. The digitized and compressed voice signal in serial data form is spread by processing it in an XOR circuit along with a chipping signal at a much higher frequency. Only disadvantage is Complex receivers, needs more complicated power control for senders.

CDMA: Code division multiple access (CDMA) is a channel access method utilized by various radio communication technologies. CDMA employs spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code) to allow multiple users to be multiplexed over the same physical channel. By contrast, time division multiple access (TDMA) divides access by time, while frequency-division multiple access (FDMA) divides it by frequency.

An analogy to the problem of multiple access is a room (channel) in which people wish to communicate with each other. To avoid confusion, people could take turns speaking (time division), speak at different pitches (frequency division), or speak in different directions (spatial division). In CDMA, they would speak different languages. People speaking the same language can understand each other, but not other people. Similarly, in radio CDMA, each group of users is given a shared code. Many codes occupy the same channel, but only users associated with a particular code can understand each other.

Multiplexing (knowing as muxing) is alarm used to refer to process where multiple analog message signals or digital data streams are combined into one signal over a shared medium. The aim is to share an expensive resource. For example, in telecommunications, several phone calls may be transferred using one wire.

Full duplex refers to the transmission of data in two directions simultaneously. For example, a telephone is a full duplex device because only one party can transmit at a time.

Most modems have a switch that lets you choose between full duplex and half duplex modes. This choice depends on which communication program you aware running.

In full duplex mode, data you transmit does not appear on your screen until it Haas been received sand sent back by other party. This enables you to validated the data the data Haas been accurately transmitted. If you display screen shows two of as each character. It probably means that your modem is set to half duplex mode when it should be in full duplex mode.

A transducer is a device, usually electrical, electronic, electro-mechanical, photonic, or photovoltaic, electromagnetic that converts one type of energy or physical attribute to another for various purposes including measurement or information transfer.

In telecommunication, the term transponder (shot- for transmitter-responder and sometimes abbreviated to XPDR, XPNDR, TPDR or TP) has the following meanings: An automatic device that receives, amplifies and retransmits a signal on a different frequency (see also broadcast translator).

An automatic device that transmits a predetermined message in response to a predefined received signal. A receiver- transmitter that will generate a reply signal upon proper electronic interrogation a communication satellite’s channels are called transponder, because each is a separate transceiver or repeater.

Building penetration: Building penetration depends on the material used for construction and architecture used. This varies building to building and is based on building construction.

Building Height Effect: The signal strength is always higher at top floor and generally floor gain height is about 2.7dB/floor which is not dependent on building construction.

Building Floor Reception: The signal isolation between floors in a multi floor building is on the average about 20dB. Within a floor of 150×150 feet, the propagation loss due to interior walls, depending on the wall materials is about 20 dB between the strong and the weak areas.

Some of the GPRS services are not likely to be provided by network operators during early deployment of GPRS due in part to the phased development of standard. Market demand is another factor affecting the decision of operators regarding which services to offer first.

Once the signal is coded, modulated and then sent, the receiver must demodulate the signal. This is usually done in two steps: Spectrum spreading (e.g., direct sequence or frequency hopping) modulation is removed. The remaining information bearing signal is demodulated by multiplying with a local reference identical in structure and synchronized with received signal.

Binary logic consists of binary variables and logical operations. The variables are designed by the alphabets such as A, B, C, x, y, z, etc., with each variable having only two distrint values 1 and 0. There are three basic logic operations that are AND, OR, NOT.

The MSB of the binary number is same as the MSB of the gray code number. So write it down. To obtain the next binary digit, perform an exclusive or operation between the bit just written down and the next gray code bit. Write down the result.

The PLA (programmable logic array) both AND and OR arrays are programmable. Costliest and complex than PAL. And array can be programmed to get desired minterms. Any Boolean functions in SOP from can be implemented using PLA.

PAL (programmable array logic) OR array is fixed and AND array is programmable. Cheaper and simpler. And array can be programmed to get desired minterms. Any Boolean functions in SOP form can be implemented using PLA.

8086 has 16-bit datd lines. 8086 is available in three clock speeds 5 MHz, 8 MHz, 10 MHz the memory space if 8086 is organized as two 512 kb banks. 8086 is 6-byte instruction queue. The 8086 can be read or write 8bit or 16bit data at a time. The I-on voltage levels for 8086 is measured at 2.5mA. 8086 as BHE (bus high enables signal).

8088 has 8bit data lines. 8088 is available in two clock speed 5 MHz, 8 MHz the memory space of 8088 is implemented as single 1mb×8 memory banks. 8088 has 4byte instruction queue. The 8088 can be read or write 8bit data at a time. The I-o voltage levels for 8088 is measured at 2.5mA. 8088 as sso (signal sign on).

The outermost shell of an atom is called valence shell and electrons in this shell are called valence electrons. Formation of energy bands occur owing to overlapping of energy levels of these valence electrons in valence shells. With the decrease in interatomic distance between the atoms in a crystal, the energy levels of electrons in outermost shells of atoms overlap to form energy bands.

The energy gap between the valence band and conduction band is known as forbidden energy gap. It is as region in which no electron can stay as there is no allowed energy state. Magnitude of forbidden energy gap in germanium and silicon is 0.72eV sand 1.12eV respectively at 300k and 0.785eV sand 1.21eV respectively at absolute zero temperature.